CVE-2026-46356
Fleet: IP spoofing allows bypassing API rate limiting
Description
Fleet is open source device management software. Prior to version 4.80.1, a vulnerability in Fleet's IP extraction logic allows unauthenticated attackers to bypass API rate limiting by spoofing client IP headers. This may allow brute-force login attempts or other abuse against Fleet instances exposed to the public internet. Fleet extracted client IP addresses from request headers (`True-Client-IP`, `X-Real-IP`, `X-Forwarded-For`) without validating that those headers originate from a trusted proxy. The extracted IP is used as the key for rate limiting and IP ban decisions. As a result, an attacker could rotate the value of these headers on each request, causing Fleet to treat each attempt as coming from a different client. This effectively bypasses per-IP rate limits on sensitive endpoints such as the login API, enabling unrestricted brute-force or credential stuffing attacks. This issue primarily affects Fleet instances that are directly exposed to the internet without a reverse proxy that overwrites forwarded-IP headers. Instances behind a properly configured proxy or WAF are less affected. Version 4.80.1 contains a patch. If an immediate upgrade is not possible, administrators should ensure Fleet is deployed behind a reverse proxy (e.g., nginx, Cloudflare, AWS ALB) that overwrites `X-Forwarded-For` with the true client IP, and apply rate limiting at the proxy or WAF layer.
INFO
Published Date :
May 14, 2026, 8:17 p.m.
Last Modified :
Oct. 26, 2026, 2:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Upgrade Fleet to version 4.80.1 or later.
- Configure reverse proxy to overwrite forwarded IP headers.
- Implement rate limiting at the proxy or WAF layer.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-46356.
| URL | Resource |
|---|---|
| https://github.com/fleetdm/fleet/releases/tag/fleet-v4.80.1 | Release Notes |
| https://github.com/fleetdm/fleet/security/advisories/GHSA-mxmp-wr3w-rvqx | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-46356 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-46356
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-46356 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-46356 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 26, 2026
Action Type Old Value New Value Added Translation Title: fleet de fleetdm, Description: Fleet es software de gestión de dispositivos de código abierto. Prior a la versión 4.80.1, una vulnerabilidad en la lógica de extracción de IP de Fleet permite a atacantes no autenticados eludir la limitación de velocidad de la API al falsificar encabezados IP del cliente. Esto puede permitir intentos de inicio de sesión por fuerza bruta u otro abuso contra instancias de Fleet expuestas a la internet pública. Fleet extraía direcciones IP del cliente de los encabezados de solicitud (’True-Client-IP’, ’X-Real-IP’, ’X-Forwarded-For’) sin validar que esos encabezados se originaran de un proxy de confianza. La IP extraída se utiliza como clave para la limitación de velocidad y las decisiones de prohibición de IP. Como resultado, un atacante podría rotar el valor de estos encabezados en cada solicitud, haciendo que Fleet trate cada intento como proveniente de un cliente diferente. Esto elude eficazmente los límites de velocidad por IP en puntos finales sensibles como la API de inicio de sesión, permitiendo ataques de fuerza bruta o de relleno de credenciales sin restricciones. Este problema afecta principalmente a las instancias de Fleet que están directamente expuestas a internet sin un proxy inverso que sobrescriba los encabezados de IP reenviada. Las instancias detrás de un proxy o WAF configurado correctamente se ven menos afectadas. La versión 4.80.1 contiene un parche. Si una actualización inmediata no es posible, los administradores deben asegurarse de que Fleet esté desplegado detrás de un proxy inverso (por ejemplo, nginx, Cloudflare, AWS ALB) que sobrescriba ’X-Forwarded-For’ con la verdadera IP del cliente, y aplicar la limitación de velocidad en la capa del proxy o WAF. -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'fleetdm', 'product': 'fleet', 'versions': [{'status': 'affected', 'version': '< 4.80.1'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-46356', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-05-14T19:38:26.554109Z'} -
Initial Analysis by [email protected]
May. 18, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Added CPE Configuration OR *cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:* versions up to (excluding) 4.80.1 Added Reference Type GitHub, Inc.: https://github.com/fleetdm/fleet/releases/tag/fleet-v4.80.1 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/fleetdm/fleet/security/advisories/GHSA-mxmp-wr3w-rvqx Types: Vendor Advisory -
New CVE Received by [email protected]
May. 14, 2026
Action Type Old Value New Value Added Description Fleet is open source device management software. Prior to version 4.80.1, a vulnerability in Fleet's IP extraction logic allows unauthenticated attackers to bypass API rate limiting by spoofing client IP headers. This may allow brute-force login attempts or other abuse against Fleet instances exposed to the public internet. Fleet extracted client IP addresses from request headers (`True-Client-IP`, `X-Real-IP`, `X-Forwarded-For`) without validating that those headers originate from a trusted proxy. The extracted IP is used as the key for rate limiting and IP ban decisions. As a result, an attacker could rotate the value of these headers on each request, causing Fleet to treat each attempt as coming from a different client. This effectively bypasses per-IP rate limits on sensitive endpoints such as the login API, enabling unrestricted brute-force or credential stuffing attacks. This issue primarily affects Fleet instances that are directly exposed to the internet without a reverse proxy that overwrites forwarded-IP headers. Instances behind a properly configured proxy or WAF are less affected. Version 4.80.1 contains a patch. If an immediate upgrade is not possible, administrators should ensure Fleet is deployed behind a reverse proxy (e.g., nginx, Cloudflare, AWS ALB) that overwrites `X-Forwarded-For` with the true client IP, and apply rate limiting at the proxy or WAF layer. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-290 Added Reference https://github.com/fleetdm/fleet/releases/tag/fleet-v4.80.1 Added Reference https://github.com/fleetdm/fleet/security/advisories/GHSA-mxmp-wr3w-rvqx